问题
解答题
在10件产品中，有3件一等品，4件二等品，3件三等品，从这10件产品中任取3件，求取出的3件产品中一等品件数X的分布列。
答案
解：由于从10件产品中任取3件的结果数为
，
从10件产品中任取3件其中恰有k件一等品的结果数为
，
那么从10件产品中任取3件，
其中恰有k件一等品的概率为P（X=k）=
，k=0，1，2，3，
所以随机变量X的分布列是
。
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在10件产品中，有3件一等品，4件二等品，3件三等品，从这10件产品中任取3件，求取出的3件产品中一等品件数X的分布列。
解：由于从10件产品中任取3件的结果数为，
从10件产品中任取3件其中恰有k件一等品的结果数为，
那么从10件产品中任取3件，
其中恰有k件一等品的概率为P（X=k）=，k=0，1，2，3，
所以随机变量X的分布列是
。
| 通读下面短文，掌握其大意,然后在各题所给的A、B、C三个选项中，选出一个最佳选项。 A young man was going to spend his holiday in a mountain village. That night he 1 at a small hotel (旅馆) near the train station. 2 going to bed, he went to the owner of the hotel and said, " Excuse me, sir. Will you please 3 me up at four forty-five tomorrow morning? I'll take the five o'clock 4 ." "Oh, sorry," the owner said in  a hurry. " I'm afraid I can't. I won't be able to get up so 5 . "The young  man was going to return to his room  6 he stopped and asked, " Have you got an alarm clock (闹钟)? Maybe it can help me." "Yes, here you a  re, young man, " said the owner.The young man thanked the owner 7 . But as he looked at the  alarm clock cl osely, it seemed there was 8 wrong with it. "Will it 9 on time? " he asked. "Sure! You just give it a good shake ( 摇晃 ) at a quarter 10 five, and it will do! " | ||||
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